This invention relates to the production of gaseous or liquid materials from subterranean formations. In one of its aspects this invention relates to altering the permeability of the subterranean formation. In yet another of its aspects this invention relates to the in situ formation of gels within a subterranean formation. In yet another of its aspects this invention relates to the use of encapsulated gelation agents for transporting gelation agents to a desired site for producing gel within a subterranean formation. In an operation for recovering hydrocarbons from subterranean hydrocarbon-containing formations penetrated by at least one wellbore, it is often desirable to alter the fluid flow paths through the formation for controlling the fluids recovered from the formation. Among examples of types of fluid control in a subterranean formation known in the art are: water shut off, directing flooding fluid flow paths to other portions of the formation, and plugging the formation. In carrying out these processes of fluid control viscous material is often pumped into the formation. It would be advantageous to be able to increase viscosity of material pumped into a subterranean formation at the points within the formation that the increased viscosity is to be used instead of being required to pump highly viscous material down the wellbore and through the formation as must be done by the processes of the prior art.
It is therefore an object of this invention to provide a method for delaying the viscosity increase in materials pumped into a subterranean formation until the extremities of the perforated formation are reached by the pumped material. It is another object of this invention to provide a method for fluid control in a subterranean formation in which gelation occurs in situ in the formation. It is still another object of this invention to provide an efficient and economical fluid control system for subterranean formations.
Other aspects, objects and the advantages of the present invention will become apparent from a study of the disclosure and the appended claims.